AISI 4140 Steel is a Chromium-Molybdenum alloy steel which widely used in Oil & Gas industry. AISI 4140 is similar to grade AISI 4130 but with a higher carbon content. SAE 4140 has greater strength and heat treatment than 4130 steel.

4140 is a 1% chromium - molybdenum medium hardenability general purpose high tensile steel - generally supplied hardened and tempered in the tensile range of 850 - 1000 Mpa (condition T).4140 is now available with improved machinability, which greatly increases feeds and/or speeds, while also extending tool life without adversley affecting mechanical properties.[PDF]